Archive for ‘SEAT: Satellite Era Accumulation Traverse’

This is one of our six camping sites. The Scott tent is the big yellow tent and the others are the sleeping tents. The bathroom is at the end of the site.

Each of our six different camping sites consisted of one cook tent, four sleeping tents, and a bathroom area (more on that later). The cook tent was a “Scott” tent, which is an enduring style and named for the polar explorer Robert Scott. It was a tight space for five people but we were able to crawl in and then sit around together with one person managing the two-burner propane stove in the corner. The Scott style tent was much sturdier than our mountain-style sleeping tents, but it was also more time consuming to put up and heavier to transport. Since we were moving nearly every other day, we wanted to keep our camp as simple and as light as possible. The Scott tent was a necessary addition for cooking, but also as a reliable shelter in the two strong storms we experienced during the traverse.

Camp with our snow machines and the radar sled.

It took a few hours to set up camp, and a similar amount of time to break it down and repack the gear on the sleds. Randy, Jessica, and I were responsible for breaking down most of the camp and for setting up some of the camp on our own while Clement and Ludo collected radar data on traverse days. Once camp was set up at a new site, we could start melting snow for water and start cooking dinner.

On a traverse day, our camp life included the take down and setup of camp, plus collecting radar data. On an ice-coring day, our camp life included digging and sampling the snow pit, drilling the ice core, and eating a hot lunch. We ate well out there! Our standard meal plan included tortellini with pesto, spaghetti with meatballs, sausage with rice and vegetables, and burritos. Sausages were popular and made their way into many meals. Special nights featured hamburgers with tater tots, and on Christmas we cooked scallops with rice and vegetables. Hot lunch on ice-coring days featured cheesy bagels fried with butter in our cast-iron pan. Since all the cheese and bread was always frozen, it required frying it all together before we could eat it – but it tasted great this way! Stormy-day food was simplified but did afford us the time to enjoy pancakes (two storms, two pancake breakfasts).

Frying cheese and bagels in butter for lunch.

The storms also affected our standard bathroom situation – usually a snow pit and tarp configuration. Ludo took the high winds and blowing snow as a challenge and created a snow-brick bathroom, which we tried our hardest to maintain from drifts!

Snow-brick bathroom and camp after a storm.

Maintaining camp and completing the science goals was a big job but we enjoyed being out on the ice sheet. For example, Christmas was a wonderful day to share together because a big storm started to clear, and we had lovely gifts to exchange, two small Christmas trees, and a very nice meal. Overall, the camp life was comfortable and enjoyable and with such a hard-working team, we were efficient at all the tasks necessary to make the camp run and be successful with the science.

Hi there! After more than three weeks spent in the field, our team is very happy to be finally back, with many memories of the traverse. This year has been a very intense experience and I would like to tell you a little more about this expedition. I will focus on the days we were doing radar surveys. Indeed, two different studies were set up during this field work. The first one was during the traverse days, where we did a radar survey from one camp to another with a range of 50-90 kilometers (31-56 miles) between the camps. On the other days the surveys were smaller, set up around each camp; they consisted of a 10-km bowtie and a 280- by 280-meter (918- by 918-ft) grid to get a better idea of the spatial variability of snow layer depth surrounding each core site. These grid surveys will show us how representative the ice core is compared to the surrounding area and help answer the question of whether we would have gotten a different result if we had drilled our ice core a few paces this way or a few paces that way. We were also looking more in detail at the layering in a 2-meter (6.56-ft) snow pit; to do that, we were using a metal plate at different depths of the snow pit.

The radar is sitting on a triangle-shape sled that is pulled by a snowmobile.

Here is a picture showing the two radars that operated simultaneously on the sled:

Both radars looked at the first 20 meters of the snow pack, sending electromagnetic waves into the snow. The snow radar (the big green horns in the picture) operates in a frequency range of 2-8 GHz. The other radar (the smaller brown horns) is the ku-band radar, sweeping between 12 to 18 GHz. The lower the frequency, the deeper the radars look. We have both radars for some redundancy in the system, imaging the snow/firn closest to the surface, which we core twice, and then the snow radar peers deeper than the cores to provide literally a deeper look. In addition to the 2 radars, we needed to know the elevation we were at, which is important for comparison with airborne data and also for modeling precipitation and temperatures. For that, we simultaneously collected GPS coordinates, which gave us our exact latitude, longitude and elevation every 5 seconds. The GPS antenna was on the very top of the sled, about 2.5 meters (8.2 feet) high.

On this sled, beside the radars sitting in the red box, we had packed: a blue bag, two black duffel bags and an orange bag. The blue bag was a survival bag, with all the gear needed in case we would have been caught in a storm; it included a tent, a stove, a shovel, and some food. The two black bags contained Ludo’s and my sleep kits, and the orange bag had some extra food, in case we were stuck for couple days. For the snow mobile, we had a repair kit under the seat to troubleshoot a possible failure. We were carrying two extra cans of gas as well. With this set-up, we were able to get a pretty light sled that was still comfortable and had all the gear we’d need in case of a storm or other circumstance separated us from the rest of the team, who were carrying all the camp gear. Fortunately, this never happened!

But now, let’s go back to the survey. The travelling days were the ones where the team was the most vulnerable: while we were traveling we had no shelters or camp set up to get back to if anything went wrong because we had to break down the entire camp in the morning, pack all gear on the sleds and ride with the snowmobiles pulling the sleds to the next camp. After driving between 50-90 km (31-56 mi), we would build our new camp, usually that same day in the afternoon. We had a total of seven travel days, covering a distance of about 500 km (310 mi).

Our sleds at camp. Strapping all your gear on the sled takes time and requires inventive skills; we called this the art of “Strapology”!

During travel days, the radar team left camp first, mostly because we had to drive at low speed to ensure the radar’s safety. Indeed, on the days we ran into large sastrugi (small ridges of hard snow), we drove at less than 10 km/h (6.2 mph). These sastrugi made our travel a little bit more difficult. Toward the end of the day, the team responsible for breaking down camp would leave the radar team and go 20 km (12 mi) ahead, to start setting up the new camp.

The days we were at camp, we did some small radar surveys: a bowtie and a grid around the core site. To help us drive the snowmobile straight for the grids, we set up flags to visualize the corners and sides. In the deep field, everything is white and flat, so it is hard to maintain a nice bearing just by following the GPS for such a small grid.

Clem and Michelle, getting ready for a short walk to set up the grid flags.

The last side survey with the radar was done in the snow pit. After analyzing the snow pit and picking up snow samples for further laboratory analysis, we used the pit to calibrate the radars and look at a detailed snow layering for the top 2 meters.

Ludo in the snow pit, sliding a metal plate in the snow at different depths. The plate creates a very bright horizon that is easily detectable on the radar return signal.

After a day of travel or after doing a grid, it is important to back up the radar data. The sleeping tents are a warm and cozy shelter to set up a “recharging station”. In addition to backing up the radar data, we recharged the satellite phone, GPS, and computer batteries.

We had to check the integrity of the radar sled at each camp site. Here is Ludo, checking the screws on one of the three legs connecting the snowboard to the sled.

To conclude, I want to say that this traverse was definitely an amazing experience and I was happy to share such a good time with the team. I am already excited to start looking at the radar data in detail to see what we can learn of the past few decades of snow accumulation in this part of the West Antarctic Ice Sheet.

Now for a recap of our adventure! We arrived in Christchurch on November 19 and returned there on January 5. We spent 17 days in McMurdo before leaving to Byrd camp on December 7. It took only a few days to prepare for the traverse and we left Byrd camp on December 10.

Team boarding the LC-130 on the way to Byrd camp at the start of the season.

Loading the sleds at Byrd camp with all of the gear we need for the traverse.

The team just about to leave Byrd camp for the traverse.

The traverse lasted 18 days, with the longest time spent at camps 4 and 5 due to the storm delays. Otherwise, we moved fast! We spent an extra day at camp 3 to drill a second ice core, but by the end of the trip we were such fast drillers that we were able to drill two cores in one day at camp 6. We drilled ice cores at nine different sites (including Byrd Station), dug and sampled 6 snow pits, and collected more than 500 km (310 mi) of radar data.

Back at Byrd, we broke down our gear and with the help of the Byrd cargo handler we had it all packed on palettes in one day. Ludo and Jessica went by Twin Otter to pick up the ice cores on the day after we returned to Byrd so that soon after the traverse ended we were finished with almost all our work! In 18 days we finished all of our science, but to achieve these goals it took near seven weeks of travel and preparation – it is not easy to do work in Antarctica!

Team after all the work for the traverse has been completed and we constructing our palette for the flight back.

At the end of the traverse we packed all the gear back on a palette to return to McMurdo.

After the traverse was finished, we could not get a flight out of Byrd Camp back to McMurdo station for a few days so we enjoyed our time with the Byrd Camp crew and rang in the new year with a gorgeous dinner and dancing with the whole camp. Then we had a fast two-day turnaround from McMurdo to Christchurch. We all worked to clean and return all the gear we used in the field and ship all of the science equipment back to the U.S. It was very satisfying to complete all of our goals and finish on time despite weather and flight delays during the season. Great work, team!!

Most members of the traverse team have made their way safely back to the U.S. Everyone took a few days to enjoy the summer sun in New Zealand and defrost before returning home. Jessica submitted this blog post and photos from the traverse, with all the scientific details on how we drill and use our firn cores to answer the following question: Is accumulation, or snow fall, changing across West Antarctica? The photos show how we drilled and processed the cores in the field and are the first set of pictures from the traverse. Next week, we will get up more photos of the camp, radar, and the Christmas storm.

Randy getting ready to drill a firn core

Here’s Jessica:

As a reminder to those following the blog, the end goal for drilling the ice/firn cores is to correlate the cores with the layering we see in the radar. (Firn is year-old snow; it’s more compacted than fresh snow but it’s not ice yet.) The radars illuminate layers that can be counted like tree rings, but those layers can sometimes be misleading, recording an individual storm event which is not a complete record of yearly accumulation. We use the physical and chemical properties of the ice core to precisely date the radar layers. Our team collected nine firn cores over a range of low to high accumulation sites this season.

The drill barrel is almost a meter long, so we sample the firn cores in increments of 75 to 90 centimeters (29 to 35 inches), and we collect about 25 increments at each site – that gives us a total sample depth of about 17 meters, or 55.7 feet, which should be equivalent to about 35 years worth of snow accumulation data, depending on the accumulation rate at the given site.

Randy and Michelle holding the drill while Jessica separates the core barrel from the chips barrel

Drilling isn’t a fast process. It takes us several hours to collect a core because we have to do some processing in the field. For each core section, we have to lower the drill into the ground until it reaches the desired depth, and once it’s done drilling, we have to pull it back up again; the deeper the hole, the longer it takes us to do this. Randy was the lead driller. He heaved the 40-lb (18-kg) drill up and down the hole for every core. He is now ready for a strongman competition! Additionally, we have to dissemble the drill barrel for each core section, to get the core out, and then we have to clean the barrel before collecting more sections.

Jessica standing in front of a firn core section.

We do some processing of the core sections in the field, and we do it differently depending on how compact the core looks. The upper meters of core are loose and are more prone to break along weaker layers, whereas the deeper the core section, the firmer and less likely to break it is. But every core section needs to have the loose snow shavings brushed off the outside of the core before we measure its bulk weight and length. The length and weight tell us the density of the snow. For the upper meters of core, we do the sampling in the field. We collect electrical conductivity measurements (a measure of the acidity content in the snow) and then we cut the core into 2-centimeter (0.8-inch) thick samples that we then measure for multiple thicknesses and diameters and bag into individual whirl-pak bags (we can measure the weights of these samples in the lab, seeing as they won’t change). Having the thickness, diameter, and weight values for each 2-cm sample is important because we can then calculate density using those parameters (the density of snow increases with depth).

Jessica cleaning the loose snow off the firn core while Randy takes a downhole depth measurement of the core hole.

Michelle and Jessica measuring the electrical conductivity of the firn cores.

Jessica cutting up the upper meter of firn while Randy bags the samples.

Jessica measuring the thickness and diameter of the cut-up firn sections.

We don’t do all this field sampling for the lower 14 meters (46 feet), which is great because your hands get very cold doing the field processing. For the lower portions of the core, we simply brush off the loose snow shavings and record bulk weight and length. After those measurements, we place the full core section in lay-flat tubing and then slid it into an insulated silver tube and put it in a snow pit to keep it cool and out of the sun until the entire core is complete. We can then wait to perform the remainder of the sampling measurements in the lab.

Jessica measuring the diameters of a full firn core section while Randy labels the protective firn core tubes.

The entire procedure of drilling and processing a firn core takes about six hours when there are three people working together (one drilling, one handling cores, and one recording the data). Randy was the driller, Michelle the handler, and I was the recorder. Once we collect all of the core sections in the tubes, we place them in insulated boxes with the individual bagged samples and a temperature logtag (records the temperature from that point until we get the cores back in the lab several months later – that way we can validate that the cores were well below freezing during the transport). We bury these boxes in a snowpit under a pile of snow to protect them from UV radiation until they are collected and stored into the ice core freezer at the WAIS Divide field camp.

Randy storing the filled silver tubes in a snow pit.

You will have to wait for Ludo’s blog to read about the recovery of the cores and transport to WAIS Divide field camp with a Twin Otter aircraft.

From the freezer at WAIS Divide the cores will then be transported by boat to the US and then to Brigham Young University, where we’ll complete all the lab measurements. In addition to the electrical conductivity and density measurements for every 2-cm sample, we’ll analyze oxygen and hydrogen isotopes that vary seasonally and are used to date the layers in the core. Using the density, layer depth and age, we can determine the accumulation rate for each core and then compare it with the radar. We are just getting in the preliminary results from last year’s cores now so with some luck, we’ll have the first preliminary results from these cores by next fall.

Greenbelt (MD, US), 3 January — On December 28 in Antarctica (which corresponds to Dec. 27 back here in the States), the team completed the traverse and arrived back at Byrd Camp with a warm welcome from the camp residents. In 18 days they had traveled 500 kilometers (310 miles), drilled eight ice cores, dug six 2-meter (6.56-ft) snow pits and set up and broken down six camps sites. And, I am guessing here, but I am sure they heaved over 20,000 shovels of snow and lifted over two tons per person while moving the science equipment, food and gear around. Ludo shoveled the most, digging the snowpits, and Randy lifted the most, hauling the ice core drill up and down while pulling each ice core to the surface. Most importantly, the team completed all planned science activities and returned safely.

The team arrived Byrd Camp at 10 AM and immediately started packing their gear in order to catch a flight out the next day. Yes, more lifting. It was going to be a very quick turnaround but the rule in Antarctica is, if a plane is on the ground, get on it! The team, along with the camp staff, had the pallet of gear built by the evening and got to enjoy a big meal from the Byrd Camp chefs. They found out early on the 29th that they would not be getting a plane that day — there had been a medical emergency somewhere else in Antarctica and the plane had been diverted there to help. No one is ever frustrated in situations like these; everyone just hopes for the best for whoever was in the incident and waits patiently for the next plane.

The next plane to McMurdo was scheduled for Jan. 2, 2012 (New Year’s Day in the States). This gave the team plenty of time to rest their arms and backs and recover from all their hard work, and gave the weather a chance to allow the Twin Otter at Byrd to retrieve the cached ice cores and empty fuel barrels at the camp site. The cores were collected and taken to WAIS Divide Camp, where they will stay in a freezer (a giant dug-out snow cave) until mid-January, when they will fly to McMurdo on a cold-deck LC-130 flight (a flight with the heater turned off). Once in McMurdo, the ice cores will wait in a freezer until the resupply ship reaches the station in February. Then they will be loaded into the ship’s freezer and sailed to Port Hueneme, California. At this point, they will be put in a freezer truck and driven to the lab in Provo, Utah, at Bringham Young University. The ice cores have a long journey ahead!

The team rang in 2012 at Byrd Camp, which only about 35 other people can claim they did, and on Jan. 2 they left for McMurdo, arriving very late that same day. I talked with the team briefly on the phone when they were in McMurdo, but they were very busy. There was a flight out at 2 AM on Jan. 4 that they were scheduled to leave on. They were all busy cleaning and returning gear, packing and shipping the science equipment back to the States and getting ready to leave Antarctica for Christchurch, New Zealand. I expect to hear if the team has arrived in Christchurch later today or tomorrow. If all is on schedule, the team is just leaving Antarctica and flying over the Ross Sea. Christchurch has been experiencing a swarm of earthquakes over the past few days but there has been no damage that would delay the team’s return. Once the team is settled in a location with good internet connectivity we will start posting their blog posts and images from the traverse, so stay tuned!